His family home belonged to relatives and only small amounts of money went through his bank accounts.

Mohammed Suleman Khan's £2.3m palace under construction - 2010

Yet while he was careful to avoid showing trappings of wealth in the UK, detectives from West Midlands Police’s Force CID discovered he had secretly paid for the £2.3 million mansion to be built in Pakistan.

In court, his defence portrayed him as a legitimate businessman who had earned around £400,000 over the nine-year period from debt collecting and other business interests in the UK and abroad.

But police found no evidence of a legitimate debt collecting company and their investigation proved he had netted over £1 million during that period, without paying the required tax and National Insurance.

A search of Khan’s Birmingham home after his arrest uncovered plans for the ‘palace’ in the Attock region of Pakistan.

The outer shell and roof of the building had been completed by Khan at a cost of £893,000.

Once finished, the property would have been valued at £2.3 million.

Khan did not utter a word during his police interviews or court appearances, aside from ‘guilty’ when he admitted cheating the public revenue during an appearance at Birmingham Crown Court in November 2013.

His honour Judge Menary QC had presided over the original case and agreed Khan was living beyond legitimate means, the most obvious evidence of that being his Pakistan property.

He said: “It is enormous with dozens of rooms, a library, servant quarter, cinema, underground parking and guard rooms. It is the size of Buckingham Palace.’’

Khan was previously twice questioned over the cold-blooded execution of a dad while he worked out at a gym in July 2004.

He was in Pakistan when Azmat Yaqub was machine gunned down in broad daylight while bench-pressing weights at a Sparkhill fitness centre.

Stunned onlookers watched helplessly as two men calmly approached Mr Yaqub and fired up to ten bullets at close range.

Police later described the brazen killing as a “cold blooded execution” and a number of suspects were questioned but later released.

They included Khan, who was arrested after flying in from Pakistan just days after the hit.

An appeal was later made on the BBC’s Crimewatch programme but Mr Yaqub’s killers have continued to evade police.